body{
    width: 100%;
    min-width: 320px;
    max-width: 640px;
    margin:0 auto;
    font-size:14px;
    font-family: -apple-system, Helvetica,sans-serif;
    color:#666;
    line-height: 1.5;
    height: 2000px;
   
}
.app{
height:45px;
}
.app ul li{
    float: left;
    height:45px;
    background-color: #333333;
    text-align: center;
    line-height: 45px;
    color:#fff;
}
ul{
    margin: 0;
    padding:0;
    list-style: none;
}
img{
    vertical-align: middle;
}
a{
    color:#666;
    text-decoration: none;
}
.app ul li:nth-child(1){
width: 8%;

}
.app ul li:nth-child(1) img{
    width:10px;

}
.app ul li:nth-child(2){
    width: 10%;
}
.app ul li:nth-child(2) img{
    width:30px;
    vertical-align: middle;
}
.app ul li:nth-child(3){
    width: 57%;
}
.app ul li:nth-child(4){
 width: 25%;   
 background-color: #F63515;
}
.search-wrap{
    position: fixed;
    height: 44px;
    overflow: hidden;
    min-width: 320px;
    max-width: 640px;
    width: 100%;

}
.search-btn{
    position: absolute;
    top:0;
    left:0;
    width:40px;
    height:44px;
   margin:14px 0 0 15px;
}
.search-btn::before{
    content: '';
    display: block;
    width: 20px;
    height: 18px;
    background: url(../images/s-btn.png) no-repeat;
    background-size: 20px 18px;
}
.search-login{
    position: absolute;
    top:0;
    right:0;
    width:40px;
    height:44px;
    color: #fff;
    line-height: 44px;
}
.search{
    position: relative;
    height: 30px;
    margin:  50px;
    border-radius: 15px;
    background-color: #fff;
    margin-top: 7px;
}

.jd_icon{
position: absolute;
width: 20px;
height: 15px;
top:8px;
left:13px;
background: url(../images/jd.png )no-repeat;
background-size: 20px 15px; 
}
.jd_icon::after{
    position: absolute;
    right:-8px;
    content: '';
    display: block;
    width: 1px;
    height: 15px;
    background-color: #ccc;
}
.sou{
    position: absolute;
    width: 18px;
    height: 15px;
    top:8px;
    left:50px;
    background: url(../images/jd-sprites.png) no-repeat;
    background-position: -81px 0;
    background-size: 200px auto;

}

.slider img{
  width: 100%;}
  .brand div{
      float:left;
width:33.33%;

  }
  .brand div img{
      width: 100%;
  }
  .brand{
    border-radius: 10px 10px 0 0;
    overflow: hidden;
  }

  nav a{
      float: left;
      width: 20%;
      text-align:center;
  }
  nav a img{
      width: 40px;
      margin: 10px 0;
      
  }
 